Various processes such as fractional distillation, fractional recrystallization, solvent extraction and the urea adduct method are known for the separation of linear fatty acids or esters from other reaction by-products. Fractional distillation is limited to the separation of fatty acids or esters of different chain lengths. Because of the small differences in the boiling points, fractional distillation is impractical for the separation of acid or ester isomers with the same chain length.
Fractional recrystallization and solvent extraction methods of separation are generally used for the isolation of saturated fatty acids from unsaturated ones.
The urea adduct method has been shown to be an efficient method for the separation of straight chain aliphatic compounds from branched chain and cyclic isomers. This method can also be used for the separation of compounds of different degrees of saturation and chain length. However, due to unfavorable economics, the urea adduct method is impractical as a commercial separation process.
The present invention is based on the discovery that dimethyl sebacate may be recovered from a reaction mixture containing it in predominant amount and minor amounts of other dimethyl esters of C.sub.10 -dicarboxylic acids by stepwise recrystallization providing certain solvents are used for that purpose.